The physics of heat and gases. Kinetic theory connects the microscopic motion of particles to macroscopic temperature and pressure, the ideal gas law ties it all together mathematically, and the first and second laws of thermodynamics govern how energy and entropy move through any system.
Six ways to master Unit 1 — pick whichever fits how you like to study.
Six topics from the College Board CED, in order.
Unit 1 builds the thermal foundation for the rest of AP Physics 2. You'll learn how the random motion of countless gas particles produces the macroscopic properties we can measure — temperature and pressure — and how the ideal gas law ties pressure, volume, temperature, and the amount of gas together in one equation.
This unit is tied for the highest weighting on the exam at roughly 15–18% of the AP Physics 2 exam (alongside Units 2 and 3). Mastering PV diagrams and the first and second laws here pays off immediately, since the same energy-accounting logic returns throughout the course.
Note: the College Board's revised Course and Exam Description numbers the AP Physics 2 units 9–15, continuing from AP Physics 1's units 1–8 — so this unit appears there as Unit 9: Thermodynamics, with topics 9.1–9.6. We number it Unit 1 since it's the first unit of the Physics 2 course.